Urea-formaldehyde condensation product and process



mama Mar. 14,1933

ISATENT OFFICE H0123, 01 WW, MASSACHUSETTS t rim-20mm: OOHDEISLTION EBODUC'I. AND PROCESS Io This invention relates to condensation products of urea formaldehyde and to processes for making such pro ucts.

' The reaction of formaldehyde upon a car- 5 bamide or a derivative thereofas urea or thiourea, results in a condensatlon product which can exist in three stagesvand the roduct of a lower stage can be converte and will of itself change b further condensation to an upper stage. n the first sta e, the

condensation product is liquid, the ispersion mixture being mostly water. If the water' is evaporated in the cold, the resultant solid is water soluble. If this SOlld is heated it becomes water insoluble. Also if the so.- lution thereof is heated, or if a small quantity of any one of several kinds of salts which act as accelerators or catalysers is added to the solution, the latter will gradually thicken and will reach, after a lapse of time which varies with the components, the

condition of a more or'less solid jelly. This is the second stage of the condensation process. In this second or jelly stage, the res n is water insoluble but is fusible. If the elly is left ex osed to the open air, and, particularly, if it is exposed'to the action of sunlight; or to heat, it will contract, lose gradually its water content, and W111 ultimately arrive at a stage where it is infusible. This is the third stage.

The conversion of the roduct from the second or jelly stage to ewthird stage bens as soon as the second stage is reached. or some purposes, it is desirable to have the condensation product at the second or jelly stage for a relatively long period of time as one or two months without any material conversion of the jell into the hard and infusible third stage. or instance, in my co endin application Serial No. 309,119, filed eptem r 28, 1928 which has matured ,into Patent No. 1,847 ,77 3 I have described a method of making a special kind of paper which involves the. use of the resin .when it is in the second and-jelly ,stage. In the manufacture of such a paper, the jelly resin is beaten u in the usua beater .an e resultant mixwith' the (pa er making fibres Application 11 1 mum: as, 1m. am 1'0. aoaiao.

ture is made into paper. It is not ractical' for commercial reasons to add the je y resin to the pa r stock in the beater as soon as the jelly 1s prepared. However, if the jell resin prepared in the usual manner is a lowed to stand even a few days before being put into the beater, it will be found that the elly has hard particles in it and that the paper made of such jelly is uneven in appearance where the hard articles have not unlted with the fibres an the remainder of theresin in the sheet. These hard particles are the result of a conversion of a .part of the jelly resin to the third or hard infusible staIge.

have discovered that the jelly resin can be maintained for a long eriod of time which is at least twomont s without any part of it being converted in any detectable manner into the third stage upon standing at ordinary room temperatures by incorporating with the jelly and specifically with the solution from which the jelly is made, a small amount of a colloidal or mucilaginous material which acts as a retarder to hinder the future condensation of the resin. This constitutes one of the objects of the present invention.

A (jelly resin which is intimately associate with a retarder can be manufactured and stored for a substantial period of time prior to use and will act as thou h the jelly resin had been freshly made. T e presence of the retarder in the jelly also influences the resultant product as for some urposes it mag be desirable to keep the resin in the secon stage for so long as is practical. I I have ound that the retarder can be a colloidal or mucila nous substance such as tragacanth gum, araya gum, India gum, starch, dextrin and the like.

In intimately associatin the retarder with the 'elly resin, I pre er to introduce the retar er into the solution before the jelly has been formed so as to insure a' homogeneous mixture of the two. If the resin jelly is made directly from the reaction between formaldehyde and urea, a solution of the retarder can be introduced into the solution of urea and formaldehydebefore the solution has been-heated to b g about the condensation and the consequent formation of the jelly resin.

I prefer, however, to make a jelly resin by the process set forth in my copending aplication Serial No. 309,118, fi ed Septemr 28, 1928. In this rocess, a urea or other carbamide. is first sub ected to the action of acetaldehyde incthe cold. The urea can be accompanied if desired by a plasticizmg a nt and an accelerator. A reaction takes p ace which produces an intermediate compound of a colloidal gelatinous. nature which I have termed A-gum. A satisfactory formula is Grams Urea O0 Glycerin 50 Acetic acid (glacial) f 10 transparent liquid or a milk In the above formula glycerin is the plasticizing agent and acetic acid is the accelerator. The glycerin may be replaced b an ester thereof as acetin and the like.

e acetic acid may be replaced by any other suitable acid or salt the roperties of accelerators being now well un erstood. To this mixture 50 grams of commercially pure acetaldehyde is added. The A-gum 1s :produced from the resultant reaction. his A-gum when cold will be either a thick rather firm solid according 'to the proportions of the ingredients in the above formula. I prefer the A-gum as a semi-liquid compound. The A- um is soluble in water. I

he desired resin jelly is prepared from the A-gum b treatlng it with formaldehyde, prefera ly in .the presence of an ac- ..celerator. A suitable formula can be as With the above proportions, the jelly resulting from the reaction is opaque and milky white, and is water insoluble but fusible, and, if it is allowed to stand, or if it is sub ected to heat, will gradually become converted into a hard insoluble and infusible resin.

To the solution re resented by the immediately above form a, and before the solution has stood long enough, as an hour, to form the 'ell solution wliic may'be made up as follows:

Parts Water 100 Karaya gum 2. 5

The A-gumformaldehyde solution to which the mucilaginous solution has been added is allowed to stand until the condensation process has been effected and the jelly resin has been formed.

I add to it a mucilaginous,

mans-rsr1 Eding converted in any detectable manner to the third or hard, so infusible condition. At the end of this period the jelly if crushed between the fingers will not give an feeling of containing grittyparticles. When the elly is incorporated with paper stock in a paper beater and made into paper in the manner disclosed in my above named application Serial No. 309,119 it will be impossible to detect on the surface of the paper any particle of jelly of any size standm up on the back ground of fibres.

y above application discloses but does not claim the combination of the jelly resin and a retarder as herein describe I claim:

1. The combination of a urea formaldejelly intoa hard infusible form.

3. The combination of a urea formaldehyde resin in a water insoluble fusible jelly form and a colloidal retarder intimately associated therewith whichacts to hinder the conversion of said jelly into a, hard infusible stage. a

4. The combination as defined in claim 3 wherein the retarder is a mucilaginous' substance.

5. The combination as defined in claim 2 wherein the retarder is Karaya gum.

6. A urea formaldehyde resin in a water insoluble jell form having a colloidal retardef to bin or the conversion of said jelly into a hard and infusible form.

7. A urea formaldehyde resin in a water insoluble fusible jelly form having incorporated therewith a mucilaginous substance which acts to retard the conversion of said resin into a hard infusible form.

8. A stable resinous condensation product of urea formaldehyde resin in an interme: diate jell stage of condensation combined with a co loidal substance that acts to hinder its further condensation beyond its jelly stage.

9. The process of making a stable intermediate resinous condensation product in a gel stage of urea and formaldehyde which consists in combining a urea with formaldeh do to form a gel in the presence of a colloidal to hinder agent which acts to hinder the condensation o the resultant product beyond said intermediate gel stage.

10. The process of making a stable intermediate resinous condensation product in a gel stage of urea and formaldehyde which consists in combining a urea with formaldehyde to form a gel and a small amount of a mucilaginous material which is present in the resultant gel and which acts therein to hinder further condensation beyond the gel stage. p v

11. The process of making a stable intermediate resinous condensation product in a 1 gel stage of urea and formaldehyde which consists in introducing a mucilaginous retarding material to a solution of a urea and formaldehyde, effecting the combination of the urea and formaldehyde to produce the 2 resultant gel which will have intimately dispersed through it said mucilaginous material which acts to preserve the gel stage of the product.

12. The process of making a stable intermediate resinous condensation product in a gel stage of a urea and formaldehyde which consists in forming an intermediate compound by the reaction of acetaldehyde upon a urea, forming a solution of said compound v with formaldehyde, introducing into this solution a mucilag'inous retarding solution, and efiectiiig the combination of: said result- I ant product with urea to form the gel which contains dis rsed therein the mucilaginous substance w 'ch hinders further condensation of the product beyond the gel stage.

In testimony whereof, I have signed my name to this specification.

40 ERNEST LIONNE. 

